1. Field of the Invention
The present invention relates to a particle analysis instrument and a computer program.
2. Description of Related Art
Automated particle analysis methods using a scanning electron microscope, an electron probe microanalyzer, or the like are known (see, for example, JP-A-2000-214112). In such an instrument, a backscattered electron image indicating a chemical composition or a secondary electron image, for example, is obtained. Particles are extracted using a contrast threshold value previously set using a reference sample. Characteristic X-rays are measured by an energy-dispersive detector or a wavelength-dispersive detector. The particles are classified using the intensity values of the measured characteristic X-rays or concentration values. This measurement is repeated for the full range of a previously set field of view, for all of a previously set number of fields of view, or for all of a previously set number of particles.
The purposes of material analysis by automated particle analysis using a scanning electron microscope or electron probe microanalyzer are roughly classified into two major categories: one is to find the average composition of a material; the other is to extract trace components from the sample. The average composition of a sample can be found, for example, by calculating the ratio of the area of particles to the total measured area of the sample.
In the above-described automated particle analysis method, the measurement is repeated for the full range of a previously set field of view, for all of a previously set number of fields of view, or for all of a previously set number of particles. At this time, there are no problems concerning the purpose of extracting trace components from the sample.
However, where the average composition of a sample should be identified, even if the ratio of the total area of extracted particles to the total area of fields of view used for analysis settles down to a constant value with the used fields of view being much smaller in number than the set fields of view, it is not possible that the present measurement is ended and the process shifts to a measurement of another analysis sample unless the measurement in the remaining fields of view is complete. Accordingly, the total analysis time may be quite long.